Capacitors are electronic components used for storing charge and energy. In their simplest form, capacitors comprise two conducting plates separated by an insulating material, e.g., a dielectric material. Capacitors can be formed using micro-electro-mechanical structures, e.g., MEMS capacitor devices. In these types of devices, the capacitor values can vary depending on the position of a beam structure, e.g., space between a moveable actuator and a fixed actuator, as well as an amount and type of insulator material used between these structures. For example, in these types of devices, one or both of the beam structure and the fixed actuator can be covered with an insulator material in order to provide a desired capacitance value.
As with many processes for forming microelectronic devices, process variations can affect the formation of the devices such that variances can be formed amongst identical devices within a wafer, a reticle field and even in a single chip. In MEMS capacitor devices, for example, capacitance variability can result which limits yield or requires large tolerances which limits usefulness of the devices. For example, MEMS lower cavity height varies radially across the wafer, due to systematic chemical mechanical polishing (CMP) variation. This lower cavity height variation causes pull-in voltage variability, which causes MEMS delta capacitance variability. To compensate for the process variations, current MEMS capacitors are screened and partitioned based on their off/on capacitance. Devices with poor tolerance are generally scrapped which significantly reduces overall wafer yield.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.